A full discussion of the chemistry of growth processes of silicon, germanium, silicon carbide, gallium nitride, gallium arsenide and sapphire is presented in this chapter. Emphasis will be given, in the case of silicon, to the details of the metallurgy of its precursor, of the chemistry of the halogenated compounds used for its preparation as an ultrapure polycrystalline material, and on the physico-chemical aspects of its melt growth. In the case of GaAs and GaN attention is, instead, dedicated to the means adopted to overcome the problems of thermodynamic stability of their molten phases, while the growth of silicon carbide is taken as an iconic example of growth from the vapour phase of a material presenting important polymorphism aspects.